Arduino power source and voltage devider

Projects General Guidance
1

Hi folks,
I am using a power source of 7.4v for my project. I have to power up Arduino uno and gsm from this source. For gsm I am connecting the battery to it using DC Jack. For arduino I am supposed to connect it to analog pin and GND to measure the battery voltage.
For this I am using one voltage divider circuit of 100E and 680K resistor.

The thing I am unable to understand is that,

without the arduino cable, the voltage measured across the analog pin A1 and GND is 3.6v and also it is not working as it is supposed to work(it needs to send the battery voltage to database). But when I am connecting the cable and opening serial monitor, the voltage reading is coming as 5v and the data is being sent to database also.

Why is it happening?

I feel that it is not reading the analog values.

How do I solve this problem?

Anyone can clear my doubts?

Thanks in Advance.

2

You should start by reading the forum guide in the "please read" sticky post, especially #11 and #15. When you have followed those instructions, we may be able to help.

3

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom... :slight_smile: